Electronic devices, such as smartphones and computers, include devices formed with one or more substrates or layers. For example, a display in a smartphone can include a display stack formed with multiple layers. The layers can include a cover glass, a polarizer, a conductive layer, a color filter, and a display layer. Conductive contacts, such as, for example, contact pads can be used to transmit electrical signals to and from various components on a layer or to a layer itself.
FIG. 1 illustrates an electrical connection between conductive contacts on two substrates. A conductive contact 100 is disposed over the front surface of a substrate 102 and another conductive contact 104 is disposed over a back surface of another substrate 106, although in some situations the contacts may be disposed over the front and back of the same substrate. A flexible cable 108 is used to form an electrical connection between the conductive contacts 100, 104. The flexible cable has a bend radius that limits how sharp the bend in the flexible cable 108 can be between the two conductive contacts 100, 104. Due at least in part to its bend radius, the flexible cable can consume considerable area in an electronic device. The amount of area consumed by the flexible cable can be an issue when the size of the electronic device is small.
Additionally, the bend in the flexible cable can produce cracks in one or more conductive traces included in the flexible cable. The cracks can be created when the flexible cable is first bent or the cracks can develop over time. Either way, the cracks in the conductive traces can prevent electrical signals from being transmitted through the entire length of the flexible cable, which can render the electronic device inoperable.
In some embodiments, a conductive layer can be electrically connected to one of the conductive contacts (e.g., 104) and a signal transmitted to the conductive layer using the conductive contact. The sheet resistance of the conductive layer, however, can cause the signal to be non-uniform across the surface of the conductive layer. This non-uniformity can adversely affect the performance of the electronic device. For example, if the conductive layer is connected to ground for electrostatic discharge (ESD) protection, the ESD protection may be ineffective due to the non-uniformity of the ground signal across the conductive layer.